Faculty

Luca Guazzotto

Research Overview

Essentially all my research career has been devoted to the study of magnetic confinement systems for nuclear fusion experiments. In particular, I am interested in the modifications that occur for the equilibrium and stability properties of plasmas in the presence of macroscopic rotation. In the last decade or so, plasma rotation has been gaining an increasing amount of attention from the scientific community, for several reasons. First, rotation is consistently observed in toroidal nuclear fusion experiments (in particular tokamaks) due to the momentum transferred to the plasma by heating systems like neutral beam injection, but somewhat surprisingly even when there is no external applied drive. Second, it is widely accepted that rotation, in particular in the poloidal direction (the short way around the torus) has a strong effect on radial energy transport. In the so-called high-confinement mode (H-mode) the radial transport is reduced by up to a factor of two with respect to standard tokamak operation (L-mode, for "low-confinement"). The effect, not yet entirely explained, is related to the presence of shear poloidal rotation. We have recently proposed a model for L-H transition that is entirely due to the effect of poloidal rotation, and which can be understood from simple one-dimensional fluid-dynamics arguments. So-called transonic equilibria (occurring in the presence of poloidal rotation) are a necessary ingredient of the theory. Moreover, plasma rotation also influences the macroscopic stability properties of plasmas. In particular, the effect of rotation on the stability of resistive wall modes (one of the instabilities that must be controlled if the next generation of experiments is going to be successful) is well documented in experiments.

A description of the two main codes I have developed (the equilibrium code FLOW and the time-dependent simulation code SIM2D) is contained in my webpage.